Lesson Overview:
In this lesson students will learn how astronomers use H-R Diagrams to classify stars. Through an online simulation demonstration, students will learn about the relationships between a star's characteristics, how to read an H-R Diagram, and how to identify the different types of stars based on their characteristics and placements on the plot. I will guide the students through the online simulation while they follow along with a worksheet drawing the plot examples that are shown to them and answering questions that correspond to the plots. Afterwards, students will get the opportunity to manipulate various stars and watching how the simulation organizes the stars they choose based on the attributes represented in the H-R Diagram. To reinforce the newly learned concepts students will get to create their own H-R Diagrams from provided data and classify the stars they plot based on their placements on the graph.
Learning Performances:
From this lesson students will be able to:
Classify stars based on the characteristics they exhibit (color, temperature, luminosity, size, age)
Classify stars by reading an interpreting an H-R Diagram
Determine a stars age by its location on the plot of an H-R Diagram
Create an H-R Diagram from interpreting provided data of stars luminosities and temperatures
Time Required:
10min – Opening graph activity and discussion
20 min – Explain about H-R Diagrams using the online simulation
10min - Activity: Students use simulation to answer questions about H-R Diagrams
10min – Discuss findings and explain homework assignment
Instructional Sequence
Introducing the lesson:
I will begin the class by asking students if they think (in general) that taller students would weigh more than shorter students. Why? If the heights and weights were to be plotted what would the graph look like? I will direct the class’ attention to an empty chart in the front of the classroom that has its axes labeled with weight and height so that students can picture the distribution of the plot. As students give their responses I will list them on the board so they can be discussed. After a brief discussion, I will plot the height and weight of a premade list of random people. This will allow the plot to display the pattern I am looking for and so that no ones feelings will get hurt by using actual height and weight information. I’ll ask the class if the pattern was what they expected and what the distribution of the plot means in terms of the relationship between these two characteristics. The chart should display a pattern where the shorter, lighter people are toward the lower left corner and taller heavier people are found towards the upper right. To activate students’ prior knowledge about stars and their life cycle, I will ask them what characteristics can be used to describe stars and what do these characteristics tell us about the age of the star? I will write the attributes given on the board. After, I will tell students how astronomers use these attributes to classify stars. I will give a brief history of how in the 1900’s the two astronomers Eljinar Hertzsprung and Henry Norris Russell plotted stars luminosities and temperatures and created a chart similar to the one made earlier class called the H-R Diagram. I will also explain how this is used to classify stars and how it is still widely used in astronomy and astrophysics. Next I will tell the class how they will be using an online simulation that will show them how the various star attributes they learned about in class can provide them with lots of information about a stars age and its life cycle. I will also explain how by just plotting an H-R Diagram you can easily determine the star’s mass, color, and age.
Instructional Activities:
After the introduction I will use an online H-R Diagram simulation to show students how stars can be classified based on the characteristics they previously learned about in class when studying the life cycle of stars. In Part 1 of the demonstration I will use the Simulation to show how stars can be classified on a graph by one attribute (color, temperature, mass, luminosity, radius). During this time students will be grouped in pairs on a computer so they can work together and follow along with me as I model certain things on the projector. During the demonstration I will provide students with handouts that require them to draw pictures of the plots we create and answer specific questions about each plot so they can demonstrate their understanding of the information displayed by the plots and so I know that they understand the information that each plot displays.
The questions for Part 1 are as follows:
1. How does the color of the star relate to the size (radius) of the star, if at all?
2. What could the color of a star possibly indicate about its temperature?
3. Does temperature of a star have any relation to its size?
4. Does the temperature of a star have any relation to its color?
5. After analyzing the two plots on temperature and color what can you infer from them about the relationship between a star’s color, size, and temperature?
Each of these questions will be discussed with the class as a whole. These questions are designed to get students thinking of what each attribute tells us about a star and what possible relationships they can have that can give us more specific information about the star. They are also designed for students to give their predications about the information of the attributes before they are plotted and the information is interpreted. While these questions are discussed out loud with the class, students will be writing the answers down on their handouts.
In Part 2, I will build on the single attributes discussed in Part 1 by plotting them against one another and taking a closer look at their relationship to one another. This will also allow us to see if we correctly predicted the relationships of the attributes from Part 1. In Part 2, I will focus on how stars can be classified by two attributes (temperature vs. color and temperature vs. mass) which is the type of display of an H-R Diagram. Again, the questions from this section will be discussed aloud and students will be required to plot the graphs seen on the projector and write down the answers to the questions.
The questions that will be asked to students are:
1. What relationship do you see between the temperature and colors of the stars?
2. What is the shape of the plot? What does that tell you about the relationship between these two attributes?
3. Is there a relationship between the mass of a star and its temperature? If so, what is the relationship?
4. Does the plot have the shape of a perfect line or is it scattered with a trend? What does that tell you about the relationship?
In Part 3 of the demonstration I will build on the information learned from Part 2 about classifying stars by two attributes and by having each pair of students use the simulation and manipulate and classify the stars based on the two attributes used in an H-R diagram (temperature vs. luminosity). Each pair will draw their plots created by the simulation on their handout and answer the following questions together about the information the plot displays.
1. How does the star at the lower right end of the main sequence compare to the star at the upper left end of the main sequence?
2. Describe the giants and supergiants. How are their radii different from main sequence stars? How are their temperatures different?
3. How do White dwarfs compare with stars in the main sequence?
4. From looking at the plots how does the luminosity of a star relate to its temperature and color?
5. By looking at the various types of stars on the plot can you predict the movement of a star on the plot as it ages?
The questions that students are answering will require them to use the prior knowledge that they’ve already learned about the different types of stars and their characteristics and apply it to what the H-R diagram displays. Students should notice where each different type of star can be found on the H-R Diagram and where it will move to as its attributes change with age (temperature, size, luminosity).
Concluding the Lesson:
After students finish Part 3 of the handout the class will regroup and the class as a whole will discuss their findings, observations, and answers to questions. Next, I will hand students a table with a listing of 12 stars along with their temperatures and luminosities. Each student will use the table to plot their own H-R Diagram on a piece of graphing paper based on the data provided for them. After they graph their data they are to use the graph to determine each star’s color, mass (heavy/light), brightness (bright/dim), and age (phase in life cycle). This assignment will be given as homework and will be completed at home.
Assessing Student Understanding:
The students will be assessed based on the following:
Ability to answer in class discussion questions
Ability to create an H-R Diagram based on the data provided for them
Ability to classify stars from interpreting the data they plotted on their graphs
The completion of the worksheet from the simulation
Answering questions correctly about the material on a quiz
Title: Classifying Stars: The H-R Diagram
Grade Level: 9th Grade
Course: Earth Science
Lesson Overview:
In this lesson students will learn how astronomers use H-R Diagrams to classify stars. Through an online simulation demonstration, students will learn about the relationships between a star's characteristics, how to read an H-R Diagram, and how to identify the different types of stars based on their characteristics and placements on the plot. I will guide the students through the online simulation while they follow along with a worksheet drawing the plot examples that are shown to them and answering questions that correspond to the plots. Afterwards, students will get the opportunity to manipulate various stars and watching how the simulation organizes the stars they choose based on the attributes represented in the H-R Diagram. To reinforce the newly learned concepts students will get to create their own H-R Diagrams from provided data and classify the stars they plot based on their placements on the graph.
Learning Performances:
From this lesson students will be able to:
Links to Standards or Benchmarks
Learning Goal 2
Materials Needed:
Time Required:
10min – Opening graph activity and discussion
20 min – Explain about H-R Diagrams using the online simulation
10min - Activity: Students use simulation to answer questions about H-R Diagrams
10min – Discuss findings and explain homework assignment
Instructional Sequence
Introducing the lesson:
I will begin the class by asking students if they think (in general) that taller students would weigh more than shorter students. Why? If the heights and weights were to be plotted what would the graph look like? I will direct the class’ attention to an empty chart in the front of the classroom that has its axes labeled with weight and height so that students can picture the distribution of the plot. As students give their responses I will list them on the board so they can be discussed. After a brief discussion, I will plot the height and weight of a premade list of random people. This will allow the plot to display the pattern I am looking for and so that no ones feelings will get hurt by using actual height and weight information. I’ll ask the class if the pattern was what they expected and what the distribution of the plot means in terms of the relationship between these two characteristics. The chart should display a pattern where the shorter, lighter people are toward the lower left corner and taller heavier people are found towards the upper right. To activate students’ prior knowledge about stars and their life cycle, I will ask them what characteristics can be used to describe stars and what do these characteristics tell us about the age of the star? I will write the attributes given on the board. After, I will tell students how astronomers use these attributes to classify stars. I will give a brief history of how in the 1900’s the two astronomers Eljinar Hertzsprung and Henry Norris Russell plotted stars luminosities and temperatures and created a chart similar to the one made earlier class called the H-R Diagram. I will also explain how this is used to classify stars and how it is still widely used in astronomy and astrophysics. Next I will tell the class how they will be using an online simulation that will show them how the various star attributes they learned about in class can provide them with lots of information about a stars age and its life cycle. I will also explain how by just plotting an H-R Diagram you can easily determine the star’s mass, color, and age.
Instructional Activities:
After the introduction I will use an online H-R Diagram simulation to show students how stars can be classified based on the characteristics they previously learned about in class when studying the life cycle of stars. In Part 1 of the demonstration I will use the Simulation to show how stars can be classified on a graph by one attribute (color, temperature, mass, luminosity, radius). During this time students will be grouped in pairs on a computer so they can work together and follow along with me as I model certain things on the projector. During the demonstration I will provide students with handouts that require them to draw pictures of the plots we create and answer specific questions about each plot so they can demonstrate their understanding of the information displayed by the plots and so I know that they understand the information that each plot displays.
The questions for Part 1 are as follows:
1. How does the color of the star relate to the size (radius) of the star, if at all?
2. What could the color of a star possibly indicate about its temperature?
3. Does temperature of a star have any relation to its size?
4. Does the temperature of a star have any relation to its color?
5. After analyzing the two plots on temperature and color what can you infer from them about the relationship between a star’s color, size, and temperature?
Each of these questions will be discussed with the class as a whole. These questions are designed to get students thinking of what each attribute tells us about a star and what possible relationships they can have that can give us more specific information about the star. They are also designed for students to give their predications about the information of the attributes before they are plotted and the information is interpreted. While these questions are discussed out loud with the class, students will be writing the answers down on their handouts.
In Part 2, I will build on the single attributes discussed in Part 1 by plotting them against one another and taking a closer look at their relationship to one another. This will also allow us to see if we correctly predicted the relationships of the attributes from Part 1. In Part 2, I will focus on how stars can be classified by two attributes (temperature vs. color and temperature vs. mass) which is the type of display of an H-R Diagram. Again, the questions from this section will be discussed aloud and students will be required to plot the graphs seen on the projector and write down the answers to the questions.
The questions that will be asked to students are:
1. What relationship do you see between the temperature and colors of the stars?
2. What is the shape of the plot? What does that tell you about the relationship between these two attributes?
3. Is there a relationship between the mass of a star and its temperature? If so, what is the relationship?
4. Does the plot have the shape of a perfect line or is it scattered with a trend? What does that tell you about the relationship?
In Part 3 of the demonstration I will build on the information learned from Part 2 about classifying stars by two attributes and by having each pair of students use the simulation and manipulate and classify the stars based on the two attributes used in an H-R diagram (temperature vs. luminosity). Each pair will draw their plots created by the simulation on their handout and answer the following questions together about the information the plot displays.
1. How does the star at the lower right end of the main sequence compare to the star at the upper left end of the main sequence?
2. Describe the giants and supergiants. How are their radii different from main sequence stars? How are their temperatures different?
3. How do White dwarfs compare with stars in the main sequence?
4. From looking at the plots how does the luminosity of a star relate to its temperature and color?
5. By looking at the various types of stars on the plot can you predict the movement of a star on the plot as it ages?
The questions that students are answering will require them to use the prior knowledge that they’ve already learned about the different types of stars and their characteristics and apply it to what the H-R diagram displays. Students should notice where each different type of star can be found on the H-R Diagram and where it will move to as its attributes change with age (temperature, size, luminosity).
Concluding the Lesson:
After students finish Part 3 of the handout the class will regroup and the class as a whole will discuss their findings, observations, and answers to questions. Next, I will hand students a table with a listing of 12 stars along with their temperatures and luminosities. Each student will use the table to plot their own H-R Diagram on a piece of graphing paper based on the data provided for them. After they graph their data they are to use the graph to determine each star’s color, mass (heavy/light), brightness (bright/dim), and age (phase in life cycle). This assignment will be given as homework and will be completed at home.
Assessing Student Understanding:
The students will be assessed based on the following:
Sources:
1. Explore learning: http://www.explorelearning.com/index.cfm?
2. Exploration Guide: H-R diagram: http://www.explorelearning.com/index.cfm?method=cResource.dspExpGuide&ResourceID=429
Teaching Resources:
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